The Saudi MOH has announced a new MERS case, this time in the capital of Riyadh involving a 43 year old expatriate male. This is the 8th case reported in 2016, and so far the authorities have not identified a known risk exposure.
While camel (or camel product) exposure has figured prominently in most of the recently reported community acquired cases, over the past 3 years the vast majority of these primary cases have unidentified risk exposures.
Last November, in EID Journal: Risk Factors For Primary MERS-CoV Infection, Saudi Arabia, we finally saw a small case-control study come out of KSA that found 33% of their subjects reported camel contact in the 14 days prior to falling ill vs. 15% in the control group.
While statistically significant, this obviously leaves a good many primary cases for whom camel contact does not appear to be a factor.
The authors of this study acknowledged these non-camel related cases, and wrote:
Other potential explanations of MERS-CoV illness in primary case-patients who did not have direct contact with dromedaries include unrecognized community exposure to patients with mild or subclinical MERS-CoV infection or exposure to other sources of primary MERS-CoV infection not ascertained in our study.
A recent nationwide serosurvey from Saudi Arabia estimated that >44,000 persons might be seropositive for MERS-CoV and might be the source of infection to patients with confirmed primary MERS-CoV illness but with no dromedary exposure (8).
For more on the possibility of there being some limited `stealth’ transmission of the virus in the community see The Community Transmission Mystery and WHO Guidance On The Management Of Asymptomatic MERS Cases.